Firearm sound suppressors work by trapping and delaying the exit of the high pressure muzzle gases from a firearm when the firearm is discharged. Creation of turbulence is one technique used to enhance the trapping of the gases with a subsequent delay in the exit of the gases from a sound suppressor. If a sound suppressor is very effective at trapping and delaying the exit of the gases, this results in a lower sound level coming from the firearm.
Firearm sound suppressors usually feature either use of discrete or individual components or a monolithic construction where the main structure is of one piece. Monolithic construction of a sound suppressor can be performed with computer numerically controlled (CNC) machinery to produce a one-piece core, referred to as a monocore, that has the baffle structure machined from one piece of metal. Sound suppressors that have a monocore with baffles are disclosed in U.S. Pat. Nos. 8,978,818 and 9,086,248.
U.S. Pat. No. 5,136,923 discloses a firearm silencer which includes an outer housing and an interior tube (a central channel) within the housing. The interior tube is spaced from the inside walls of the housing to form an exterior chamber around the interior tube. The interior tube is adapted to receive a projectile discharged from a firearm and extends the entire length of the housing which is attached to a muzzle of a firearm. The interior tube is perforated with a plurality of rows of ports which extend through the wall of the interior tube and discharge into the exterior chamber. The sound suppressing performance of this type of suppressor is considered to be due to the rapid heat exchange between the propellant gases and the surface area of the conductive metal in the suppressor. The efficiency of this type silencer is considered greater on a volume basis for a given projectile clearance than that of baffle silencers. However, because of the limited surface area inherent in this type of design, this type of suppressor is useful only for small fire arms. A sound suppressor of this design having substantially increased surface area for a given volume, for heat dissipation, and that could create greater turbulance of the gases around the length of the interior tube, would be much more effective in suppressing sound and attenuating recoil.
U.S. Pat. No. 9,599,421 improved on the design disclosed in U.S. Pat. No. 5,136,923 by providing a central channel having a circular central bore, through which a projectile passes, and a rectangular external shape with four sides with openings thereon. Each side rotates 60 to 120 degrees around the longitudinal axis of the central bore, forming a helical twist in the central channel. Chambers extend from the central channel and form the same helical configuration as the central channel, producing a helical flow of propellant gases, coming out of the central channel, from a rear end to a front end of the central channel. This design improves sound suppression and accuracy of the firearm.
A double helix configuration of a sound suppressor may further improve sound suppression and accuracy of a firearm but heretofore has not been available.